Gearbox

ABSTRACT

A hydraulic pump arrangement ( 1 ), has a hydraulic pump ( 2 ) with two flow directions. The hydraulic pump ( 2 ) has a first hydraulic port ( 3 ) and a second hydraulic port  4 . A first feed line ( 5 ) and a first discharge line ( 6 ) are, both connected to the first hydraulic port ( 3 ). A second feed line ( 7 ) and a second discharge line ( 8 ), are both connected to the second hydraulic port ( 4 ). A non-return valve ( 9, 10, 11, 12 ) is arranged in each feed line ( 5, 7 ) and in each discharge line ( 6, 8 ).

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to German Patent Application No.102011055194.1, filed Nov. 10, 2011. The entire disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The disclosure relates to a gearbox with a hydraulic pump arrangementthat has a hydraulic pump with two flow directions. The hydraulic pumphas a first hydraulic port and a second hydraulic port. In this case,the hydraulic pump arrangement is formed such that it functionsindependent of rotational direction. Accordingly, hydraulic fluid isdelivered through a discharge in both possible flow directions.

BACKGROUND

A hydraulic pump arrangement is known from DE 10 2010 010804 A1. Thedisclosed hydraulic pump is arranged in a housing flange portion of agearbox. The housing flange portion covers a recess of the gearboxhousing. The housing flange portion has an axially projecting extensionwhere several modules of the hydraulic pump are arranged axially onebehind the other. Furthermore, bores and valves are provided in thehousing flange portion, which enables delivery of the hydraulic fluidindependent of the rotational direction.

SUMMARY

It is object of the present disclosure, to provide a specifically simplestructure for a rotational independent hydraulic connection of thehydraulic pump arrangement.

The object is achieved by a gearbox with a hydraulic pump arrangementthat comprises a hydraulic pump with two flow directions. The hydraulicpump has a first hydraulic port and a second hydraulic port. Thehydraulic pump arrangement includes a first feed and a first discharge,both of which are connected to the first hydraulic port. A second feedand a second discharge are connected to the second hydraulic port. Anon-return valve is arranged in each feed and in each discharge.

The feeds of the hydraulic pump arrangement are connected to an oil sumpof the gearbox. Thus, oil can be delivered from the oil sump of thegearbox to the lubricating points of the gearbox or to furthercomponents to be lubricated.

The hydraulic pump is driven by a drive shaft of the gearbox. The driveshaft of the gearbox includes at least one gear. The gearbox has agearbox housing with a housing bottom. The oil sump is arranged in thehousing bottom. An accommodation chamber is provided in the housingbottom to accommodate the gear of the drive shaft. The accommodationchamber separates the oil sump into a first sump chamber and into asecond sump chamber. The first feed of the hydraulic pump arrangement isconnected to the first sump chamber. The second feed of the hydraulicpump arrangement is connected to the second sump chamber.

The non-return or check valves in the feeds open in the direction to therespective hydraulic port. The non-return or check valves in thedischarges close in the direction to the respective hydraulic port. Ifthe hydraulic pump is driven in one direction where the suction side isat the first hydraulic port and the pressure side is at the secondhydraulic port, the non-return valve in the first feed opens. Thenon-return valve in the first discharge closes, as this is laid out toclose in the direction to the first hydraulic port. Thus, hydraulicfluid is sucked in from the first feed. On the pressure side, at thesecond hydraulic port, the non-return valve at the first dischargeopens. The non-return valve in the second feed closes, as this onlyopens in the direction to the second hydraulic port. Thus, it is closedby the hydraulic pressure against this direction.

In the other case, where the hydraulic pump is driven such, that thepressure side occurs at the first hydraulic port and the suction sideoccurs at the second hydraulic port, the non-return valve in the firstfeed is closed and the non-return valve in the first discharge opens.However, the non-return valve in the second feed is opened and thenon-return valve in the second discharge is closed. Thus, hydraulicfluid is pumped from the second feed to the first discharge.

In a preferred embodiment, both discharges are connected to a jointdischarge line. Thus, the hydraulic pump arrangement has only onedischarge line and one discharge port in spite of the two discharges.Preferably, the hydraulic pump is a gear pump, a vane pump or a pistonpump.

The two sump chambers can be connected to each other via a connectionpassage. The accommodation chamber for the gear of the drive shaft isnecessary for a compact design. The gear of the drive shaft has to bearranged as close as possible to the lower gearbox bottom of the gearboxhousing. This means, however, that without an accommodation chamber, thegear of the drive shaft would enter the oil of the oil sump and wouldcatapult the oil upwards due to rotation. In this case the danger existsthat air would be sucked in by the oil pump because of the agitated oil.To prevent this, the accommodation chamber extends up to the level ofthe oil sump or just below the oil level of the oil sump. Thus, the oilthat flows to lubricate the gears of the gearbox flows, downwards due togravity, partially directly into the oil sump and also into theaccommodation chamber. In the accommodation chamber, the oil is thencatapulted upward due to the rotation of the gear of the drive shaft.The oil is, preferably, catapulted over a wall of the accommodationchamber up to an outer wall of the gearbox housing. From here, the oilflows directly into the oil sump. No gear of the gearbox enters the oilin the oil sump. Thus, settling of the oil takes place and no dangerexists that air will be sucked in by the hydraulic pump arrangement.

Preferably, the hydraulic pump has a pump housing, that is detachablyconnected to the gearbox housing. Thus, a compact design of the gearbox,including the hydraulic pump arrangement, is ensured. Alternatively, thepump housing can also form part of the gearbox housing, in the form of ahousing extension.

The pump housing can have two inlet openings, that are connected to thebores in the gearbox housing leading to the sump chamber. The non-returnvalves of the feeds are arranged in the bores of the gearbox housing.

The hydraulic pump can be modularly constructed and can include an inletmodule, a pump module and an outlet module. The modules are detachablyconnected to each other. Connection passages, that extend from inlets tothe hydraulic pump, are provided as part of the feeds in the inletmodule. The hydraulic pump, especially the gears of a gear pump, isprovided in the pump module. In the outlet module, connection passagesare provided as part of the discharges. The connection passages extendfrom the hydraulic pump to a joint outlet of the discharges. Thus, by asimple exchange of the individual modules, the hydraulic pump can beadapted to different requirements. Different large pump modules withdifferent outputs can be provided. Thus, depending on the necessarydelivery output, a corresponding pump module can be used. As the pumpmodule is not part of the gearbox or of the gearbox housing, no specialcast pieces need to be provided that have to be adapted to the differentpump outputs. The individual modules are, respectively, encapsulated tothe outside or sealed, so that they represent their own housing.Depending on the pump output, the whole hydraulic pump, consisting ofthe individual modules, will differ in length.

A pump drive shaft is provided for the drive of the hydraulic pump. Thedrive shaft is passed from the pump module to the inlet module. The pumpdrive shaft is passed through a bore in the gearbox housing and is,drive-wise, detachably connected within the gearbox housing to a driveshaft of the gearbox.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

In the following, a preferred embodiment is described in detail by usingthe drawings. It shows

FIG. 1 is a schematical representation of a hydraulic circuit of ahydraulic pump arrangement according to the disclosure;

FIG. 2 is a longitudinal sectional view through a portion of a gearboxwith a hydraulic pump arrangement according to the disclosure;

FIG. 3 is an exploded view of the hydraulic pump arrangement of FIG. 2;

FIG. 4 is a cross-sectional view of a pump module of the hydraulic pumparrangement of FIG. 2;

FIG. 5 is a top plan view of an inlet module of the hydraulic pumparrangement of FIG. 2;

FIG. 6 is a cross-sectional view of the outlet module of the hydraulicpump arrangement of FIG. 2; and

FIG. 7 is a cross-sectional view of a portion of a gearbox of FIG. 2 inthe area of the accommodation chamber.

DETAILED DESCRIPTION

In FIG. 1 the hydraulic circuit of a hydraulic pump arrangement 1, toachieve a pump effect independent of direction of rotation, according tothe disclosure is schematically shown. The hydraulic pump arrangement 1includes a hydraulic pump 2 in the form of a gear pump with a firsthydraulic port 3 and a second hydraulic port 4. The first hydraulic port3 is connected to a first feed line 5 and a first discharge line 6. Thesecond hydraulic port 4 is connected to a second feed line 7 and asecond discharge line 8. In each of the respective feed lines 5, 7 anddischarge lines 6, 8 there is arranged a non-return or check valve 9,10, 11, 12. The two feed lines 5, 7 are connected via a joint feed lineor are separately connected to an oil sump 13 or to an oil reservoir.The two discharge lines 6, 8 are connected to a joint discharge line 14.Alternatively, for each discharge line 6, 8, also separate dischargelines can be provided. The non-return valve 9 in the first feed line 5opens in the direction to the first hydraulic port 3. The check valve 9closes in the direction towards the oil sump 13. The non-return valve 11in the second feed 7 opens towards the second hydraulic port 4 andcloses in the direction to the oil sump 13. Thus, the two non-returnvalves 9, 11 of the two feed lines 5, 7 open towards the hydraulic pump2.

The non-return valve 10 in the second discharge line 8 opens towards thedischarge line 14. The check valve 10 closes in the direction to thesecond hydraulic port 4. The non-return valve 12 of the first dischargeline 6 opens in the direction to the discharge line 14 and closes in thedirection to the first hydraulic port 3. Thus, the two non-return valves10, 12 of the two discharge lines 6, 8 close, respectively, in thedirection to the hydraulic pump 2 and open in the direction to thedischarge line 14.

As indicated by the arrows of the hydraulic pump 2, the hydraulic pump 2can be driven in two rotational directions. In a first rotationaldirection, hydraulic fluid is pumped from the first hydraulic port 3 tothe second hydraulic port 4. The first hydraulic port 3 is, thus, thesuction side and the second hydraulic port 4 is the pressure side. Thus,a vacuum is present at the first hydraulic port 3. The vacuum opens thenon-return valve 9 of the first feed line 5 in the direction to thefirst hydraulic port 3. Furthermore, the non-return valve 12 of thefirst discharge line 6 is closed because of the vacuum at the firsthydraulic port 3.

At the pressure side, the side of the second hydraulic port 4, thenon-return valve 10 in the second discharge line 8 is opened because ofexcess pressure in the direction to the discharge line 14. At the sametime, the non-return valve 11 of the second feed line 7 closes. Thus,the hydraulic fluid is delivered from the oil sump 13 through the firstfeed line 5 via the hydraulic pump 2, to the second discharge line 8 andfurther to the discharge line 14.

When the hydraulic pump 2 is driven in a second rotational direction,which is in an opposite direction to the first rotational direction, thesuction side is produced at the second hydraulic port 4. The pressureside occurs at the first hydraulic port 3. Thus, the non-return valve 10of the second discharge line 8 is closed because of the vacuum at thesecond hydraulic port 4 in direction to the hydraulic pump 2. Instead,the non-return valve 11 in the second feed line 7 is opened in directionto the second hydraulic port 4. Thus, hydraulic oil is delivered fromthe oil sump 13 via the second feed line 7 to the second hydraulic port4. At the pressure side, the side of the first hydraulic port 3, thenon-return valve 9 of the first feed line 5 is closed because of theexcess pressure in direction to the oil sump 13. Furthermore, thenon-return valve 12 of the first discharge line 6 is opened in directionto the discharge line 14. Thus, the hydraulic fluid is delivered fromthe first hydraulic port 3 via the first discharge line 6 to thedischarge line 14.

Thus, depending on the rotational driving direction of the hydraulicpump 2, oil is delivered from the first feed line 5 to the seconddischarge line 8 or from the second feed line 7 to the first dischargeline 6. However, in both directions it is ensured, that the oil isdelivered from the oil sump 13 to the discharge line 14. Thus, oil isalways delivered, independent of the rotational driving direction of thehydraulic pump 2.

FIG. 2 shows a partial cross-sectional view through a gearbox 15 with agearbox housing 16. A drive shaft 18 with a gear 24 is, besides othershafts, rotatably supported in the gearbox housing 16. The drive shaft18 exits in a sealed manner from the gearbox housing 16. The drive shaft18 is formed as a hollow shaft. A drive trunnion 19 is inserted into thehollow shaft-like drive shaft 18. The drive trunnion 19 connects thedrive shaft 18 to a drive unit for driving the gearbox 15. In this case,it is preferably a power-take-off shaft of a tractor, which is connectedvia a universal joint shaft to the drive trunnion 19.

The gearbox housing 16 has a bore 20 at the side opposite the drivetrunnion 19. The bore 20 is closed by the hydraulic pump arrangement 1.The hydraulic pump arrangement 1 is flanged via attachment screws 17 tothe gearbox housing 16. The hydraulic pump arrangement 1 has a pumpdrive shaft 21 to drive the hydraulic pump 2. The pump drive shaft 21 ispassed through the bore 20 into the inside of the gearbox housing 16.The pump drive shaft 21 is, drive-wise, directly connected via ashaft-hub-connection to the drive shaft 18. Thus, the hydraulic pump 2is directly driven by the drive shaft 18 of the gearbox 15. Thus, it isdirectly driven by the drive unit driving the gearbox 15.

The gearbox housing 16 has a gearbox bottom 23. The oil sump 13 isformed in the gearbox bottom 23. The oil is accumulated in the oil sump13. The oil has, within an accommodation chamber 63 (see FIG. 7), an oillevel 25 that is indicated by the dotted line.

FIGS. 3 to 6 show the hydraulic pump arrangement 1 and its individualcomponents in detail and are described in the following together.

The hydraulic pump arrangement is structured modularly and has an inletmodule 26, a pump module 27 as well as an outlet module 28. Theindividual modules 26, 27, 28 are connected to each other by locatingpins 29, 30 and connecting screws 31, 32.

FIG. 4 shows a cross-sectional view of the pump module 27. In this view,the hydraulic pump 2, in the form of a gear pump has a first gear 35 anda second gear 36. The two gears 35, 36 mesh with each other. Thehydraulic pump 2 is formed as a conventional gear pump. Furthermore, thefirst hydraulic port 3 and the second hydraulic port 4 are formed in thepump module 27.

The first gear 35 is, drive-wise, connected to the pump drive shaft 21.Thus, the first gear 35 represents the driven gear 35. The second gear36 is driven by the first gear 35 and is supported via a bearing shaft37. The bearing shaft 37 is held and supported in the inlet module 26and in the outlet module 28.

FIG. 5 shows a top plan view of the inlet module 26. In the inlet module26, a first inlet opening 33 is provided. The first inlet opening 33 isaligned with a first bore in the gearbox housing 16 of the gearbox 15and thus, hydraulically connected to it. The first inlet opening 33 isconnected via a connection passage in the form of a first bore 38 to afirst outlet opening 39. The first outlet opening 39 is aligned with thefirst hydraulic port 3 of the pump module 27 and hydraulically connectedto it. The first inlet opening 33, the first bore 38 and the firstoutlet opening 39 form part of the first feed line 5 of FIG. 1. Thenon-return or check valve 9 of the first feed line 5 is arranged in thefirst bore of the gearbox housing 16, which also forms part of the firstfeed line 5.

Furthermore, the inlet module 26 has a second opening 34 that isconnected via a connection passage, in form of a second bore 40, to thesecond outlet opening 41. The second inlet opening is aligned with asecond bore of the gearbox housing 16 and thus hydraulically connectedto it. The second outlet opening 41 is aligned with the second hydraulicport 4 of the pump module 27 or the hydraulic pump 2 and thus, ishydraulically connected to it. The second inlet opening 34, the secondbore 40 and the second outlet opening 41 form part of the second feedline 7 of FIG. 1. The non-return or check valve 11 is arranged in thesecond bore of the gearbox housing 16, which also forms part of thesecond feed line 7.

In the inlet module 26 several connection bores 44, 45, 46, 47 areprovided, to accommodate the locating pins 29, 30 and the connectingscrews 31, 32. Besides these connecting screws, further, not shown,screws are provided. Furthermore, at the inlet module 26, the attachmentscrews 17 (FIG. 2) can be passed through attachment bores 48, 49. Thisenables the inlet module 26 to flange to the gearbox housing 16.

A through bore 42 serves to enable passage of the pump drive shaft 21through the gearbox housing 16. A bearing bore 43 serves to accommodatethe bearing shaft 37.

FIG. 6 shows a cross-sectional view through the outlet module 28. Theoutlet module 28 has a first inlet opening 50 that is hydraulicallyconnected to a connection passage in the form of a first bore 52. Thefirst bore 52 extends from the outside up to the first inlet opening 50.The first inlet opening 50 is aligned with the first hydraulic port 3 ofthe pump module 27. Furthermore, the non-return or check valve 10 ofFIG. 1 is arranged in the first bore 52. The first inlet opening 50 andthe first bore 52 form part of the first discharge line 8 of FIG. 1. Theoutlet module 28 includes a second inlet opening 51 that ishydraulically connected to a connection passage in the form of a secondbore 53. The second bore 53 is formed identically and parallel to thefirst bore 52. The non-return or check valve 10 of FIG. 1 is arranged inthe second bore 53. The second inlet opening 51 is aligned with thesecond hydraulic port 4 of the hydraulic pump 2 in the pump module 27.The second inlet opening 51 and the second bore 53 form part of thesecond discharge line 8 of FIG. 1.

The two bores 52, 53 are hydraulically connected to a discharge line 54.The discharge line 54 is in the form of a bore extending transversallyto the two bores 52, 53. For this, the first bore 52 and the second bore53 cross the discharge line 54. The openings of the bores 52, 53 areclosed at the ends facing away from the inlet openings 50, 51 by dummyplugs 56, 57. The discharge line 54 ends in a discharge opening 55.

The outlet module 28 includes bearing bores 58, 59 to accommodate thepump drive shaft 21 and the bearing shaft 37. A connection bore 60 isshown that threadably receives one of the connecting screws 32.

FIG. 7 shows a cross-sectional view of the gearbox housing 16 in thearea of the oil sump 13. Here it is visible, that two inner housingwalls 61, 62, starting from the housing bottom 23, extend upwards andform an accommodation chamber 63. The accommodation chamber 63accommodates the gear 24 of the drive shaft 18. The accommodationchamber 63 is open towards its top to enable a tooth meshing of the gear24 with a further gear 64 of the gearbox. Between the outer housingwalls 65, 66 and the inner housing walls 61, 62, two sump chambers 67,68 are formed. Oil is accumulated in the two sump chambers 67, 68. Theoil levels are indicated by the dotted lines 69, 70. Oil, that flowsinto the accommodation chamber 63, is catapulted by the gear 24 of thedrive shaft 18 upwards, so that it is thrown over the inner housingwalls 61, 62. The oil then flows into the sump chambers 67, 68. In thiscase, for example, different oil levels, which furthermore varytemporarily, can be found in the accommodation chamber 63 and in thesump chambers 67, 68. The sump chambers 67, 68 serve as settlingchambers, to prevent a sucking-in of air into the hydraulic pumparrangement. In each of the sump chambers 67, 68, respectively, a bore72, 73 is visible. The bores 72, 73 are connected to the inlet openingsof the hydraulic pump arrangement. The non-return valves 9, 11 of thefeed lines 5, 7 are arranged in the bores 72, 73.

To be able to maintain the oil level in both sump chambers 67, 68 at thesame height, a connection passage 71 is provided to connect the two sumpchambers 67, 68. The connection passage 71 extends transversally to thedrive shaft 18 and is visible in FIG. 2.

The description of the disclosure is merely exemplary in nature and,thus, variations that do not depart from the gist of the disclosure areintended to be within the scope of the disclosure. Such variations arenot to be regarded as a departure from the spirit and scope of thedisclosure.

What is claimed is:
 1. A gearbox, comprising: a hydraulic pump with twoflow directions, the hydraulic pump includes a first hydraulic port anda second hydraulic port, a first feed line and a first discharge lineare both connected to the first hydraulic port; and a second feed and asecond discharge are both connected to the second hydraulic port; anon-return valve is arranged in each feed line and in each dischargeline, the feeds are connected to an oil sump of the gearbox; a gear boxdrive shaft drives the hydraulic pump, the drive shaft of the gearboxincludes at least one gear; a gearbox housing includes a housing bottom,wherein the oil sump is arranged in the housing bottom; an accommodationchamber is provided in the housing bottom for accommodating the gear ofthe drive shaft, the accommodation chamber separates the oil sump into afirst sump chamber and into a second sump chamber; and the first feedline of the hydraulic pump arrangement is connected to the first sumpchamber and the second feed line of the hydraulic pump arrangement isconnected to the second sump chamber.
 2. The gearbox according to claim1, wherein the non-return valves in the feed lines open in the directionto the respective hydraulic port and the non-return valves in thedischarge lines close in the direction to the respective hydraulic port.3. The gearbox according to claim 1, wherein the first discharge lineand the second discharge line are connected to a joint discharge line.4. The gearbox according to claim 1, wherein the hydraulic pump is agear pump, a vane pump or a piston pump.
 5. The gearbox according toclaim 1, wherein the hydraulic pump has a pump housing, that isdetachably connected to the gearbox housing.
 6. The gearbox according toclaim 5, wherein the pump housing has two inlet openings that areconnected to bores leading into the sump chambers in the gearbox housingand the non-return valves of the feed lines are arranged in the bores ofthe gearbox housing.
 7. The gearbox according to claim 1, wherein thehydraulic pump further comprises an inlet module, a pump module and anoutlet module, the modules are detachably connected to each other, andconnection passages are provided in the inlet module as part of the feedlines, the connection passages extend from inlets to the hydraulic pump,the hydraulic pump is provided in the pump module and connectionpassages are provided in the outlet module as part of the dischargelines, the connection passages extend from the hydraulic pump to adischarge line.
 8. The gearbox according to claim 7, wherein a pumpdrive shaft for driving the hydraulic pump is passed from the pumpmodule through the inlet module.
 9. The gearbox according to claim 8,wherein the pump drive shaft is passed through a through bore in thegearbox housing and is, drive-wise, detachably connected within thegearbox housing to the drive shaft.
 10. A gearbox, comprising: ahydraulic pump, a first feed line and a second feed line both feedingoil to the hydraulic pump, the feed lines are connected to an oil sumpof the gearbox, a gearbox drive shaft drives the hydraulic pump, thedrive shaft of the gearbox includes at least one gear, a gearbox housinghas a housing bottom, the oil sump is arranged in the housing bottom, anaccommodation chamber is provided in the housing bottom to accommodatethe gear of the drive shaft, the accommodation chamber separates the oilsump into a first sump chamber and a second sump chamber, the first feedline is connected to the first sump chamber and the second feed line isconnected to the second sump chamber.
 11. The gearbox according to claim10, wherein the hydraulic pump has two flow directions and a firsthydraulic port and a second hydraulic port, the first feed line and afirst discharge line are both connected to the first hydraulic port andthe second feed line and second discharge line are both connected to thesecond hydraulic port, and a non-return valve is arranged in each feedline and in each discharge line.